Leveling jack for vehicle

ABSTRACT

A leveling jack for a vehicle, such as a recreational vehicle, includes a leveling piston and cylinder, a bi-directional, reversible pump, and a reservoir within a common sealed housing that does not require exterior fluid connections. The piston is extended from the housing to contact the ground and effect leveling by operating the pump in one direction, and is retracted into the cylinder by operating the pump in the other direction. Accordingly, the leveling jack is a self-contained unit, and does not require a central hydraulic unit and the necessary hoses between the jack and the central hydraulic unit as needed in the prior art.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims domestic priority based upon U.S. Provisional patent application Ser. No. 61/205,668, filed Jan. 22, 2009, the disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a leveling and stabilization system for a motor vehicle, such as a recreational vehicle.

2. Description of the Background of the Invention

When a recreational vehicle is parked for use, it is desirable that the vehicle be leveled and stabilized for the convenience of the inhabitants. Accordingly, it has become common to provide stabilization and leveling systems for recreational vehicles. Commonly, these systems provide multiple leveling jacks (usually four) located on opposite corners of the vehicle. A centralized hydraulic system mounted within the vehicle is used to effect leveling and stabilization. The centralized hydraulic system includes a pump, reservoir, and appropriate hydraulic lines connecting the pump to the jacks located at each corner of the vehicle. Such systems are shown in U.S. Pat. Nos. 4,061,309; 4,165,861; 4,597,584; 4,743,037 and 4,746,133. In addition to the foregoing, which disclose hydraulic leveling systems, electric leveling jacks have also been used, as shown in U.S. Pat. No. 6,722,635.

The hydraulic leveling systems using a centralized hydraulic system are relatively complex in construction and operation, and are costly to install and maintain. Furthermore, hydraulic lines connecting the pump to the jacks are exposed to damage on the exterior of the vehicle. Furthermore, the pump, hydraulic manifold, hydraulic valves (usually four or more), all hydraulic hose assemblies and fittings, pressure switches, wiring harness, etc., are relatively bulky and the space needed inside the vehicle to house the centralized hydraulic system used is not insignificant. In addition, the centralized hydraulic system requires the user to top off hydraulic fluid and to bleed air from the system.

SUMMARY OF THE INVENTION

The present invention provides a leveling jack for leveling and stabilizing a vehicle of the above-described type in which a leveling cylinder, a pump, and a fluid reservoir are all sealed within a common housing. It is contemplated that four of these jacks will be used as described above; however, since each of the jacks is a sealed unit, no hoses or fittings are necessary to connect the jacks to a centralized hydraulic system, and since both the pump and reservoir are within each sealed unit, the hydraulic manifold, centralized pump, and centralized reservoir are not needed. The piston within the housing of the present invention includes a piston rod which extends from the housing to engage the ground surface (the housing itself is mounted on the surface of the body of the vehicle) the pump is a reversible, bi-directional pump that extends the piston rod from the housing when the pump is operating in one direction and retracts the piston rod into the housing when the pump is operating in the reverse direction. According to a second embodiment of the invention, a second adult single-acting piston includes a rod extending from the housing to engage ground surface and a spring which retracts the rod.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a leveling jack made pursuant to the teachings of the present invention;

FIG. 2 is a cross-sectional view taken substantially along lines 2-2 of FIG. 1, taken through the piston intermediate the top and bottom portions of the apparatus;

FIG. 3 is a view taken substantially along line 3-3 of FIG. 2;

FIG. 4 is a view taken substantially along line 4-4 of FIG. 2;

FIG. 5 is a view taken substantially along line 5-5 of FIG. 2;

FIG. 6 is a view similar to FIG. 1, but illustrating a different embodiment of the invention;

FIG. 7 is a schematic illustration of the hydraulic system used in the embodiment of FIGS. 1-5; and

FIG. 8 is a schematic illustration of the hydraulic system used in the embodiment of FIG. 6.

DETAILED DESCRIPTION OF INVENTION

Referring now to FIGS. 1-5 of the drawings, the leveling jack 10 includes a housing 12 consisting of a leveling cylinder 14, a pump unit 16, and an end cap 18 extending between the leveling cylinder 14 and the pump unit 16. Although the leveling cylinder 14, pump unit 16, and end cap 18 are illustrated as separate components, housing 12 may be made as a single cast unit. Leveling cylinder 14 is defined by a circumferentially extending outer wall 20 which slidably receives a piston 22, to which a piston rod 24 is attached, which extends out of lower end 26 of the leveling cylinder 14. The end of the piston rod 24 extending out from the housing is attached to a ground engaging plate 28, which rests on ground when the leveling jack is used. A mounting bracket 30 is attached to the outer surface of the outer wall 20, and is aperatured to facilitate attachment to an exterior surface of a vehicle, such as a recreational vehicle, which uses the leveling jack 10.

The cap 18 is attached to the top of the leveling cylinder 14 by bolts 32, 34, and 36. Bolts 32 and 34 are conventional, but bolt 36 is provided with a transverse passage 38 which intersects with longitudinal passage 40. A passage 42 of about the same diameter as the bolt 36 extends along outer wall 20 and is provided with an opening 43 that extends through the wall 20 to permit fluid communicated through the passage 38 and 40 of the bolt 36 to communicate in the annular retraction chamber 44 defined between the piston rod 24 and the inner circumferential surface of the outer wall 20. Piston 22 cooperates with the end cap 18 to define an extension chamber 46. When fluid pressure is communicated into extension pressure chamber 46, piston 20 and piston rod 24 are urged downwardly viewing the Figures, thereby extending the lower end of piston rod 24 out of the leveling cylinder 14. Conversely, when pressure is communicated into the annular retraction pressure chamber 44, the piston 20 is urged upwardly viewing the Figures, thereby withdrawing the piston rod into the cylinder 14. The pump unit 16 includes a housing 48 in which a bi-directional, reversible pump 50 (which will be hereinafter described) and a bi-directional, reversible motor 52 for driving the pump 50 are mounted, the motor 52 is connected to the pump 50 to operate the latter. The pump 50 cooperates with end cap 18 to define a reservoir 54 therebetween. A pair of tubes 56, 58 (only the tube 56 being shown in FIG. 2) extend through the reservoir 54 to communicate the pump 50 to passages 60, 62 (FIG. 3) extending within the end cap 18.

Relief valves 64, 66 prevent over-pressure in the passages 60, 62. Passage 60 is communicated into the extension pressure chamber 46 through opening 68, and the passage 62 is communicated into the annular retraction pressure chamber 44 through the passages defined within the bolt 36. Check valves 70, 72 are mounted in the passages 60, 62 and permit flow into the corresponding pressure chambers 44, 46, but normally prevent flow from the pressure chambers. Shuttle piston 74 is slidable within a bore extending between the passages 60, 62 and is provided with offset faces 76, 78, which are exposed to the pressure levels in the passages 60, 62 respectively. Accordingly, when passage 60 is pressurized, the shuttle 74 is shifted to hold the check valve 72 open, thereby permitting fluid to vent from the annual retraction chamber 44, and when the passage 62 is pressurized, the shuttle piston 74 shifts to hold the check valve 70 open, thereby permitting fluid to vent from the extension pressure chamber 46.

Referring now to the pump 50, a commutator 80 is non-rotatably mounted in a pump block 82 and is circumscribed by a rotor 84 which is mounted in pump block 82 for rotation relative to the commutator 80. A roller bearing 86 is mounted in the pump block 82 and circumscribes the rotor 84, but the center of rotation of the rotor 84 is offset from the center of the roller bearing 86. Accordingly, the clearance between the rotor and the roller bearing at point A (FIG. 5) is greater than the clearance between the rotor and the rotor bearing at point B, and the clearance tapers between points A and B. Notches 88, 90 are provided in the commutator 80 and are communicated to the tubes 56, 58 respectively. Circumferentially spaced pistons 92 are mounted in corresponding circumferentially spaced bores 94 and slide relative to the rotor. Accordingly, as each piston 92 approaches the point of maximum clearance A, fluid is drawn in through notch 90 and passage 58, and as the rotor continues rotation, the corresponding piston is urged inwardly, toward the commutator, thereby discharging fluid through the corresponding notch 88 and tube 56 assuming rotation in the clockwise direction. The pistons are maintained in contact with the inner race of the bearing 86 by centrifugal force. Accordingly, when the motor is reversed in the opposite (counterclockwise) direction, fluid is drawn in through notch 88 and its corresponding tube and is discharged through notch 90 and its corresponding tube. A pin 95 drives the rotor by its connection with plate 98 that is turned by the motor 52. Passages 96 extend through the pump block 82 to communicate make-up fluid to the rotor 84.

Referring to FIG. 7, operation of the leveling jack is illustrated diagramatically. The dashed lines connecting the check valve 70 with tube 58 and check valve 72 and tube 56 represent the operation of the shuttle piston 74. Check valves 98 are located in passages 96, but are not shown in other drawings, to permit fluid to be withdrawn from the reservoir 54 by the pump 50 when necessary. A valve 100 connects the tube 56 to reservoir 54 through a relief valve 102. The valve 100 is a pressure operated valve and is connected to the pressure in tubes 56, 58. When the piston 22 is being retracted into the extension pressure chamber 46, a greater amount of fluid is discharged from chamber 46 than is admitted into chamber 48, because of the volume consumed by piston rod 24. Accordingly, when the pressure in tube 58 indicates the chamber 44 is being pressurized, valve 100 is switched to permit communication into the reservoir, but when the pressure chamber 46 is being pressurized, valve 100 is in the position illustrated, blocking communication to the reservoir 54.

The embodiment in FIG. 6 is substantially the same as that of FIGS. 1-5, except that a single-acting piston is used instead of the double-acting piston illustrated in FIGS. 1-5. Accordingly, in the embodiment in FIG. 6, the annular chamber 44 is vented to atmosphere, and the piston is returned when pressure in pressure chamber 46 is released by a spring 106. Accordingly, tube 58 is stubbed off, and the pump 50, when driven in one direction, pressurizes extension pressure chamber 46 to drive the piston rod outwardly and when the pump is driven in the reverse direction, pressure in tube 58 holds check valve 70 open, thereby releasing the pressure in chamber 46, permitting the spring 106 to withdraw the piston into the housing.

This invention is not limited to the details above, but may be modified within the scope of the following claims. 

1. Leveling jack for establishing clearance between a body surface and a ground surface comprising a piston, a fluid pump and a fluid reservoir within a common sealed housing mounted on one of said surfaces, said piston being slidable in said housing and including a piston rod extending from the housing to engage the other of said surfaces to control the clearance between said body surface and ground surface in response to sliding of the piston; and an internal fluid passage within said housing communicating said pump, said piston and said reservoir without fluid communication into said housing from a source exterior of the housing.
 2. Leveling jack as claimed in claim 1, wherein said housing includes a leveling cylinder defining a bore slidably receiving said piston, said piston rod extending from one end of said bore, said piston cooperating with one end of said bore to define a pressure chamber.
 3. Leveling jack as claimed in claim 2, wherein said pump is mounted in a pumping chamber defined within said housing, said reservoir being defined within said pumping chamber.
 4. Leveling jack as claimed in claim 3, wherein said pumping chamber is defined within a cylinder having an end closed by a cap also closing said one end of said bore, said passage being defined in said cap.
 5. Leveling jack as claimed in claim 4, wherein said pump is mounted in said chamber and cooperates with said end of the chamber to define said reservoir.
 6. Leveling jack as claimed in claim 4, wherein said Valve is a check valve mounted within said cap.
 7. Leveling jack as claimed in claim 2, wherein said pump is a reversible pump operable in one direction to pump fluid into said pressure chamber through said valve and in the other direction to allow fluid to withdraw from said chamber, and means for holding said valve open when the pump is operated in the other direction.
 8. Leveling jack as claimed in claim 7, wherein said piston is a double acting piston in which said piston rod cooperates with the wall of said housing to define an annular chamber therebetween, another passage communicating said pump to said annular chamber, said pump when operated in said other direction pumping fluid into said annular chamber and allowing fluid to withdraw from said annular chamber when the pump is operated in said one direction.
 9. Leveling jack as claimed in claim 8, and another valve in said another passage to control fluid communication into said annular chamber, and means responsive to the fluid pressure level in the passage communicated with the pressure chamber to open said another valve when fluid is being pumped into the pressure chamber.
 10. Leveling jack as claimed in claim 7, wherein said piston is a single acting piston, and a spring yieldably urging said piston toward said one end of said one end of said bore.
 11. Leveling jack as claimed in claim 7, wherein said pump is mounted in a pumping chamber defined within said housing, said reservoir being defined within said pumping chamber between said pump and an end of the pumping chamber, said passage including a tube extending through said reservoir.
 12. Leveling jack for establishing clearance between a body surface and a ground surface comprising a piston, a reversible fluid pump and a fluid reservoir within a housing mounted on one of said surfaces, said piston being slidable in a bore defined within said housing and including a piston rod extending from the housing to engage the other of said surfaces to control the clearance between said body surface and ground surface in response to sliding of the piston, said piston cooperating with one end of the bore to define an extending pressure chamber therebetween, and passages within said housing communicating said pump and said pressure chamber and with said extending pressure chamber with said reservoir, and a first valve within said passage communicating into said extending pressure chamber when the pump is operated in one direction, but preventing communication out of said extending pressure chamber when the pump is operated in said one direction.
 13. Leveling jack as claimed in claim 12, wherein a valve operating member responsive to operation of said pump in the other direction opens said first valve to allow communication from said pressure chamber to said reservoir when the pump is operated in the other direction.
 14. Leveling jack as claimed in claim 12, wherein said piston is a double acting piston cooperating with opposite ends of said bore to define said extending pressure chamber between said piston and one end of said bore and an opposite retracting pressure chamber between said piston and the other end of the bore, said passage including a first branch communicating said pump to said extension pressure chamber and a second branch communicating said pump to the retracting pressure chamber, said first valve being mounted in said first branch.
 15. Leveling jack as claimed in claim 14, wherein said first valve controls communication into said extending pressure chamber when the pump is operated in said one direction, and a second valve mounted in said second branch controlling communication into said retracting pressure chamber when the pump is operated in the other direction.
 16. Leveling jack as claimed in claim 15, wherein valve control means opens said first valve to allow communication to said reservoir when the pump is operated in said other direction and opens said second valve to said reservoir when said pump is operated in said one direction.
 17. Leveling jack as claimed in claim 12, wherein said piston is a single acting piston responsive to fluid pressure in said extending pressure chamber to extend said piston rod from said housing, and a spring yieldable urging said piston in a direction retracting said piston into said housing.
 18. Leveling jack as claimed in claim 17, wherein valve control means holds said first valve open to communicate said extension pressure chamber to reservoir when the pump is operated in the other direction.
 19. Leveling jack for establishing clearance between a body surface and a ground surface comprising a housing mounted on one of said surfaces, a piston slidable in said housing and extending therefrom to engage the other surface to control the clearance between said surfaces in response of sliding of said piston in said housing, said piston cooperating with said housing to define an extending pressure chamber therebetween, a reversible fluid pump and a reservoir communicated with said extending pressure chamber, a first valve communicating said extending pressure chamber with said pump but preventing communication out of said extending pressure chamber when the pump is operated in said one direction, and a valve operating member responsive to operation of said pump in the other direction to open said first valve to allow communication from said pressure chamber to said reservoir when the pump is operated in the other direction.
 20. Leveling jack as claimed in claim 19, wherein said piston is a double acting piston cooperating with opposite ends of said bore to define said extending pressure chamber between said piston and one end of said bore and an opposite retracting pressure chamber between said piston and the other end of the bore, said passage including a first branch containing said first valve communicating said pump to said extension pressure chamber and a second branch communicating said pump to the retracting pressure chamber, and a second valve in said second branch communicating said pump with the retracting pressure chamber when the pump is operated in the other direction, said valve operating means acting on said second valve to permit communication from the retracting pressure chamber when the pump is operated in said one direction.
 21. Leveling jack as claimed in claim 19, wherein said piston is a single acting piston responsive to fluid pressure in said extending pressure chamber to extend said piston rod from said housing, and a spring yieldable urging said piston in a direction retracting said piston into said housing.
 22. Leveling jack as claimed in claim 21, wherein valve control means holds said first valve open to communicate said extension pressure chamber to reservoir when the pump is operated in the other direction. 